Characterization of intracellular metabolites of axenic amastigotes of Leishmania donovani by 1H NMR spectroscopy.

The intracellular metabolites of long-term in vitro cultured axenic amastigotes of Leishmania donovani (strain Dd8) were determined and compared with those of promastigotes and intracellular amastigotes, employing proton NMR spectroscopy. The presence of two new metabolites, i.e. betaine and beta-hydroxybutyrate were reported. Betaine was detected in all the three stages being highest in the promastigotes while beta-hydroxybutyrate could be detected only in promastigotes and axenic amastigotes. Among other metabolites, succinate and valine were found in higher quantities in intracellular amastigotes and axenic amastigotes than in promastigotes. Acetoacetate was present only in axenic and intracellular amastigotes. The comparative metabolite profile of different parasite forms reveals that axenic amastigotes seem to represent an intermediate stage between promastigotes and intracellular amastigotes in spite of their strong resemblance to intracellular amastigotes in morphology, infectivity, biochemical studies and even in the manifestation of amastigote specific A2 protein.